A day after trading charges in their first debate, Senator Scott Brown and Democratic challenger Elizabeth Warren charted two different courses on Friday: Brown intensified his attacks, while Warren rallied voters with the help of her newly minted supporter, ­Mayor Thomas M. Menino.

Amplifying an argument that he made in Thursday night’s debate, Brown sought to undercut Warren’s reputation as a consumer advocate by highlighting her work as an attorney for an insurance company in an asbestos lawsuit.

“Huge insurance corporations don’t hire big-time attorneys from Harvard to fight against their interests for their opponents, which would be the victims,” Brown told ­reporters at his South Boston headquarters.

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Hours later, Warren ­received Menino’s coveted endorse­ment at a rally in Roslindale, where the diverse crowd of hundreds, dotted with union members and city workers, underscored the impor­tance Menino’s political machine can have in turning out voters in close races.

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The mayor had for months resisted entreaties from members of his party to endorse Warren, a fellow Democrat. Menino and Brown, a Republican, have a close relationship, and the mayor has often praised the senator as a gifted and hard-working politician.

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But at the rally in Roslindale, Menino said Warren won his admiration when he heard her talk about the foreclosure crisis and her support for President Obama’s jobs bills. He ­also praised her support for the president’s health care law and said she earned his ­respect by standing up to congressional Republicans and some members of Obama’s own Cabinet to create the ­Consumer Financial Protection Bureau.

“Elizabeth Warren has got my vote, and she’s got my help,” Menino said, as he stood on a stage with his wife, ­Angela. “I know Scott Brown. I like Scott Brown. But we disagree about some very important, very basic things. I think government should still be about the business of helping people.”

Warren welcomed the mayor’s backing. “I am proud to have you, the toughest fighter Boston has ever seen, standing in my corner,” Warren said, as she turned to face Menino. “Know this, Mayor Menino, I will not let you down.”

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The mayor, seeking to dispel doubt about his enthusiasm for Warren, said his vaunted get-out-the-vote operation would be running at full speed for her in November. “My team will be on the ground starting tomorrow morning,” he told reporters. “They will be out there working hard.”

With her arm looped through Menino’s, Warren pressed in close and said, “The mayor said today, ‘We’re going to win this, kid.’ And I believe him.”

With polls showing the candidates locked in a tight race, Menino’s ability to marshal his supporters to knock on doors and encourage voters to get to the polls could make a difference for Warren in November.

Brown downplayed the significance of Menino’s endorsement, pointing out that he has the backing of former mayor Raymond L. Flynn of Boston, as well as former Democratic mayors of Lowell, Worcester, and Springfield, and other Democratic politicians around the state. He even made a point of praising Menino.

“I consider Mayor Menino a friend, somebody I have a lot of respect for,” Brown said. “I’m going to continue to try to earn the respect of the mayor, and let the voters know that, regardless of that endorsement, I’m going to be working for the city of Boston.”

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In the press conference at his headquarters, Brown sought to keep the focus on Warren’s role in the asbestos lawsuit. He stood before a bank of television cameras and held up papers that showed the $212,000 Travelers Insurance paid Warren for her work in the case.

Brown said Warren’s advocacy on behalf of the insurance giant flies in the face of her reputation for sticking up for “little guys.”

As the Globe reported in May, Warren did represent Travelers in the 2009 asbestos case, but at the time, the company was seeking to unlock a $500 million settlement ­account for victims, a step many victims supported. After Warren’s work on the case had ended, however, Travelers won a separate court ruling that ­allowed the company to avoid paying out the settlement. That ruling is under appeal.

“Elizabeth Warren got involved to protect the settlement,” against a challenge from another insurance company, said David J. McMorris, a lawyer at Thornton & Naumes in Boston, who represented victims in the case.

McMorris and several officials from an asbestos workers’ union showed up outsideBrown’s headquarters to ­defend Warren’s role in the lawsuit.

“It should be very, very clear the victims would have no chance to get paid by ­Travelers were it not for the work of Elizabeth Warren,” McMorris told reporters. “She’s been with the victims then, and she’s with the victims now.”

McMorris has donated $467,435 to Democratic politicians, according to the Brown campaign, which sent out a press release about McMorris’s contributions minutes after his comments.

Meanwhile, Thursday night’s fiercely fought debate continued to be scrutinized for what impact it might have on the race.

Rob Gray, a Republican political consultant, said he believed the debate was “pretty much a draw” with “no blood taken from either candidate.” He said he believed Warren spent so much time attacking Brown’s votes that she failed to lay out a positive vision of her own agenda.

“When she does that, she makes herself susceptible to the same criticism that Mitt Romney’s getting, that he’s purely negative,” Gray said.

He also said Brown may have been too pointed in his attacks.

“I thought he needed to be aggressive and he maybe came off as a little more aggressive than he needed to be,” Gray said. “His biggest asset is high favorables, so he’s got to be careful not to take it too far.”

On the other side of the aisle, Scott Ferson, a Democratic consultant, said he didn’t see any problem with Brown’s tone. “There was nothing he did that was out of bounds,” he said. “And I don’t think voters are that protective that [candidates] can’t be questioned aggressively.”